For a conventional, automatically wound watch, winding is achieved by the rotation of an oscillating weight whose radius is approximately equal to that of the movement and which pivots at the centre of and above said movement. In such case, the oscillating weight is normally formed of two distinct parts: the weight support and the heavy sector. The weight support carries the heavy sector on the periphery thereof and, at the centre thereof pivots on an arbour that forms the suspension of the entire oscillating weight. This support is generally made of brass or German silver and is deliberately made to be flexible to avoid damaging the oscillating weight suspension in the event of a shock. Here the weight support plays the part of a shock absorber.
One method of making the weight support flexible is disclosed in CH Patent No. 279 001. Here the heavy sector is carried by at least two resilient arms, which pivot on the same point of the frame, so that any axial shocks to the weight are absorbed by the resilience of the arms.
The heavy sector of a conventional large radius system is the external part of the oscillating weight and it is integral with the weight support to which it is screwed, riveted or crimped. It is formed of a sintered alloy or of precious metal with a large volumic weight.
When there is a low intensity shock, the resilience of the weight support is sufficient to protect the system from the impact. In the event of a high intensity shock, the movement of the oscillating weight is limited by the heavy sector pressing on the plate in one direction and on the back cover of the case in the other direction. The weight support, which is often decorated, is thus not liable to be scratched.
It has, however, already been proposed to limit the shake of the weight by stop members that are fitted in the oscillating weight and have rounded, polished parts, which project relative to the surface of said weight, so that, in the event of hard shocks, the weight does not touch the back cover of the case or the top of the plate. This embodiment is described in CH Patent No. 331 275.